The contract for building a nuclear power station at Hinkley Point might not be “valid”, a leading legal academic has warned.

Tim Yeo, who chairs the energy and climate change select committee, was forced to defend the government’s biggest nuclear energy deal after David Howarth, a Cambridge academic and Liberal Democrat MP, said that the deal will fall foul of European law.

Mr Howarth, a law and policy professor at the University of Cambridge, said that the 35-year deal with EDF Energy, which guarantees a price for EDF’s electricity that is 40 per cent higher than current prices if EDF